Abstract
Determining the age of ancient architectural and cultural monuments is a significant scientific problem. An approach based on the transformation of portlandite into calcite and subsequent recrystallization of calcite is considered, which allows for estimating the relative age of ancient brickworks for local groups of historic buildings based on the results of diffraction studies of powder samples of carbonate mortars and measurements of samples with a known age. This article presents the results of the study of lime mortars of ancient brickwork. Under natural conditions, the process of transformation of portlandite into calcite takes from 100 to 200 years. The rate of this process is influenced by temperature, humidity, peculiarities of interaction with carbon dioxide contained in the air, etc. Examples show that portlandite is completely transformed into calcite in masonry mortars of the 18th century and that portlandite is not found in older mortars. It was determined that after the transformation of portlandite into calcite, an increase in the degree of recrystallization of calcite is observed, which manifests itself in powder diffraction patterns in the relative broadening of the diffraction peak of calcite hkl 104. In a detailed study, an estimate of the peak width at half maximum (FWHM) associated with the degree of crystallinity is effective. The actual data are given, which show that in older lime mortars the degree of recrystallization of calcite is higher than in younger ones. This fact makes it possible to indirectly determine the relative age of brickwork and masonry of various buildings of architectural heritage, which is especially relevant for the objects with the use of lime mortars of the northern provinces of the Byzantine Oecumene and other periods of various cultures.
Highlights
Lime binders and masonry mortars based on them are among the first to be widely used by humanity in its construction history to construct brick and masonry
—was not detected, which manifests itself in the diffraction patterns withto not detected, which manifests itself in the diffraction patterns with peaks corresponding peaks corresponding to. This is due to its complete transition to calcite
At magnifications of up to 200 times, calcite looks like a chalky, powdery, highly porous mass, the general background shows that the process of recrystallization is in progress (Figure 9a,b)
Summary
Lime binders (air and hydraulic lime, Roman cement) and masonry mortars based on them are among the first to be widely used by humanity in its construction history to construct brick and masonry. Lime mortars became a mass and ubiquitous building material during the period of the Roman Empire. Lime-based mortars and lightweight concrete (LC) have been used successfully since ancient Roman times and have gained popularity due to their excellent physical and technical properties [1]. The widespread use of lime mortars is primarily due to their properties, relatively simple production technology, and relatively widespread distribution of raw materials for their production—various carbonate rocks (limestones) and small aggregates. Most people who look at ancient brick or masonry in architectural heritage sites always ask questions: “When was it done? Estimating the age of ancient historical, cultural, and architectural heritage is a complex and essential scientific problem and requires an integrated approach and the use of various research methods
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